[FW][ADD] MRP: One-step manufacturing

[fw-bot]

This PR adds a new doc detailing how to manufacture products using one step.

NOTE: There is a ref tag in this doc that does not currently work because the doc it is referencing is not yet live. The doc being referenced should be live by the time this doc is published, at which point, the ref tag will work.

Forward-Port-Of: #5158

[robodoo]

Pull request status dashboard.

[fw-bot]

@hojo-odoo cherrypicking of pull request #5158 failed.

stdout:

Auto-merging content/applications/inventory_and_mrp/manufacturing/management.rst
CONFLICT (content): Merge conflict in content/applications/inventory_and_mrp/manufacturing/management.rst

stderr:

01:15:31.562845 git.c:463               trace: built-in: git cherry-pick ac95d3a643e80c86eb3530c9cb9958b8991ff6a4
error: could not apply ac95d3a64... [ADD] MRP: One-step manufacturing
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".
----------
status:

Either perform the forward-port manually (and push to this branch, proceeding as usual) or close this PR (maybe?).

In the former case, you may want to edit this PR message as well.

More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port

[StraubCreative]

@StraubCreative
solution: merge all 2-step fwps on #6402 first then cherry pick 1-step and 3-step on top

[StraubCreative]

@robodoo r+